They really, really work. My experience as a student in a psychiatric hospital before and after the introduction of antidepressant drugs convinced me of that very early in my career. A few years involved in conducting controlled trials of new drugs in very depressed patients reinforced that belief, and I've not had any cause to change my mind since, when dealing with depression in general practice. How they work is still a matter for debate. The most recent explanation is that they may encourage the production of new nerve cells in the hippocampus, part of the brain known to be concerned with mood, including depression and elation. Their effect isn't instantaneous - most take several weeks to produce their maximum impact - but the time between starting antidepressants and beginning to feel better is shortening as newer drugs become available.

A little red wine every day is said to help us avoid heart attacks and strokes, and may help prevent dementia, but once we start to fail mentally, is it still beneficial? My father is resistant to giving up his 'tot' at night, but he is getting very forgetful.

Apart from being cruel to stop him drinking now, it could also be counterproductive. Italian specialists in ageing report that older people who drink a glass of wine every day are less likely than teetotallers to progress from normal forgetfulness into serious dementia. I presume they were drinking Italian wine and that the same results apply to an evening tot.

Do you have a question for Dr Smith? Email doctordoctor@guardian.co.uk